When House Republicans gather for a private conclave at the Capitol Wednesday to map out their strategy for dealing with immigration reform, they will have plenty of options to choose from—and an obstacle blocking each one.

The House GOP could take up the Senate bill that passed June 27 with strong bipartisan support, which includes changes to immigration enforcement, security and visa policies the party has long sought. But Republican leaders have vowed not to. It can scramble to complete an alternative comprehensive bill, but efforts to do so have sputtered for months. The most likely scenario is for the House to junk comprehensive reform and adopt a piecemeal approach many members prefer, but which Democrats have ruled out.

In short, the Senate’s giant step forward two weeks ago has collided with the brick wall of the Republican-controlled House. For supporters of immigration reform, the elation has given way to grudging acceptance of the hard slog ahead. Backers who once boasted the bill would be on President Obama’s desk this summer are now conceding the battle is likely to rage at least into the fall. And despite the powerful forces arrayed behind the bill, no one seems certain how the House will handle it. “I don’t know what’s going to happen,” says Republican activist Grover Norquist, who supports the Senate bill. “There’s not some obvious end game.”

It’s not any clearer to the players inside the Capitol. “We’re all over the map,” says Republican Rep. Raul Labrador, a former immigration lawyer from Idaho who has become an influential voice within the conference on the issue. “We can end up with another Obamacare if we don’t do this right.”

A path may emerge after the House Republican summit Wednesday, where House leaders will attempt to suss out the concerns of rank-and-file members so that it can plot a path forward. On Tuesday, however, the GOP is split over what constitutes the right approach.

One faction would consider supporting a path to citizenship, which Democrats insist upon, if certain enforcement standards are assured. Others want modest reforms, and are open to legalizing some of the 11 million people estimated to be living the U.S. illegally, like the so-called DREAMers, but not until enforcement benchmarks are met. Another bloc of as many as 50 Republicans is resistant to doing anything at all. “I don’t see enthusiasm to do a large-scale path to citizenship,” says Oklahoma Republican James Lankford, a member of the House GOP leadership.

Without one, Democrats have threatened to walk. “Without a path to citizenship, there is not going to be a bill,” New York Democrat Chuck Schumer, the lead Democratic negotiator, said Tuesday. For months, a popular theory held that the House would pass one or more small-scale bills, then send those measures to a conference with the Senate, where a path to citizenship could be slipped in, setting up a bipartisan vote engineered by House and Senate leaders. But Schumer on Tuesday shot down that notion.

“To go to conference with various pieces without a path to citizenship … is a path to a cul-de-sac, to no immigration bill,” Schumer told reporters. “I don’t think you can get Democrats to vote for things without a path to citizenship. It was our bottom line from the beginning.”

Part of this is theatrical sparring, with both sides observing the Washington ritual of retreating to your corners to issue ultimatums before making moves to the middle. But the lines being drawn make a deal more difficult. If Republicans won’t offer a path to citizenship and Democrats won’t go to conference without one, there is little room for compromise. “Then it dies,” Labrador shrugs. “If something dies because it doesn’t have a path to citizenship, it will be the Democrats’ fault for being unreasonable.”

For their part, backers of the bill believe that the political incentives for the GOP are tilted so heavily toward reform that enough House Republicans will buckle. “The business communities want it. The communities of faith want it. The political consultant class, which tells you what the Republican Party needs, wants it. Even if you can get re-elected in your monochromatic House district, you don’t get to govern” if immigration blocks a path to the White House, Norquist says. “This is team ball.”

“If Boehner and a critical mass of leaders in the House decide the future of the GOP depends on it, there is a bipartisan majority that can pass the bill,” says Frank Sharry, executive director of America’s Voice, a pro-immigration reform group. “If Boehner and company can’t figure out how to get to yes, they’re going to make a historic mistake.”

But Sharry concedes that advocates may have to prepare for “Plan B”—a campaign to batter Republicans in 2016 for derailing the best shot at reform in a generation. Meanwhile, the White House could mull whether to take executive action to issue work permits to large numbers of workers, as he did for hundreds of thousands of young immigrants at the height of the 2012 election.

But as House Republicans meet, Democrats are left with few cards to play, having already handed over concessions on citizenship, border security and visa programs during Senate negotiations. “You can have a House bill that has cosmetic differences from the Senate bill,” says Sharry. “But if it’s significantly further to the right, you won’t get the Democrats to vote for it. So I do think it’s the Senate bill or a reasonable facsimile that is the end point.”

Meanwhile, key members of the Republican pundit class are ramping up their campaign to scuttle reform. “There is no case for the bill, and certainly no urgency to pass it,” conservative writers Bill Kristol and Rich Lowry wrote in a a joint op-ed published Tuesday. “If Republicans take the Senate and hold the House in 2014, they will be in a much better position to pass a sensible immigration bill.”

Kristol and Lowrey are in the minority among establishment Republican figures, but their argument for waiting to address immigration is gaining currency among House Republicans. “I’d rather identify the issues we agree on and work on those,” Rep. Lankford told reporters. “If we have issues we can’t settle, let’s put them off for another year.”

Advocates of immigration reform are weary of waiting. And though the optimism of recent weeks has dimmed, advocates say the campaign remains on track. With a bill this large, on a topic that has bedeviled lawmakers, a deal “will look like it’s about to fall apart at least three times before it gets done,” Norquist says. Supporters must hope he is right, because as it stands now, more paths seem to lead to failure than final passage.